As a method of achieving a large capacity memory, a shift register type magnetic memory is proposed. Unlike a conventional semiconductor memory in which each memory cell includes a storage element, a selection element, and wiring for obtaining information, the shift register type magnetic memory transfers stored information to the locations of a sensor and wiring.
In shift register memories that have been proposed, the shift operation has been performed by using a current pulse flowing through a shift register. However, it is not easy to shift information of all the digits using a current pulse without fail. In particular, in a case where information of 100 digits or more is dealt with in order to achieve a large capacity memory, the physical length of the shift register increases, resulting in that the possibility of the occurrence of malfunction increases due to the unsharpening of current pulse waveform caused by the capacitance or inductance component.
In order to drive a magnetic domain by current pulse, a large current density of about 1×107 A/cm2 is required. In particular, in a case of a shift register with 100 digits or more, the length of magnetic nanowire increases, thereby increasing the resistance value. As a result, a high voltage is required to generate current pulses. There is a fear in that this would prevent the memories from having a large capacity.